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15he 

Florida. Buggist 

Official Organ of the Florida Entomological Society 

VOL. Ill SPRING NUMBER NO. 4 

March, 1920 

(Printed in April) 



-MOSQUITOES FOUND ABOUT GAINESVILLE, FLA. 

By U. C. LOFTIN 

Part II. — Traps For Mosquitoes 

During the fall and winter of 1912-1913, the writer, at the 
suggestion of Dr. E. W. Berger,** conducted some experi- 
ments with traps for adult mosquitoes. These experiments 
have been recorded in an unpublished thesis, submitted at the 
University of Florida. The principle results are summarized 
here. The traps (simplified forms of the one used by Lefroy) 
were vessels and boxes, dark inside and of several sizes and 
shapes, placed where the mosquitoes would be likely to use 
them for hiding places in the early morning. A successful 
style was a plain earthenware jar, or crock, such as is often 
used for churns, six to eight inches in diameter, sixteen to 
eighteen inches high, dark chocolate to black inside (Fig. 27). 



♦Third and final consecutive installment of Mr. Loftin's paper. 

**Dr. Berger first used the traps during June and part of July, and then placed 
his records at the writer's disposal. 



The Kny-Scheerer Corporation 

Department of Natural Science 
404-410 W. 27th Street, New York, N. Y. 



Entomological Supplies of Every Description 
We buy and sell rare insects. Illustrated catalogue on request. 

We recommend the goods advertised in The Florida Bug-gist. 
Please mention Buggist when you write our advertisers. 



54 The Florida Buggist 

Another type that gave good results was wooden boxes, seven 
by seven inches square by thirteen inches deep, painted black 
or dark green inside, or lined with black or dark green cloth. 
A joint of six-inch stovepipe was also used with good results. 
Other sizes, shapes and colors of crocks and boxes were used, 
but it was found that the traps of small diameter and a depth 
of twice the diameter gave the largest catches. No noticeable 
difference was found between the black and the dark green 
cloth, but the cloth lined boxes gave slightly better results than 
the painted ones. It is well known that mosquitoes seek a 
dark place in which to hide during the day and anything that 
furnishes this condition and is nearly air-tight so that they 
can be easily killed with a fumigant can be successfully used. 
Mosquitoes, in common with living things in general, are 
positively phototactic up to a certain degree of light intensity, 
and negatively so after this is exceeded. With mosquitoes this 
optimum, or turning point, is commonly met a little before 
sunrise. 

The traps were placed in various positions and kept un- 
covered during the night. They were covered from 7:00 to 
7 :30 in the morning, before the direct rays of the sun reached 
them. A board or piece of stiff cardboard makes a good cover, 
but the best and most convenient cover found was a wooden 
frame covered with wire gauze with a piece of cardboard cut 
to fit. This cover allows an examination of the contents and 
the addition of the killing agent without any danger of escape. 
Gasoline was found to be the cheapest and most effective 
fumigant. It was added at the rate of 1/2 teaspoonful per 
gallon capacity of the crock, and about twice this amount for 
the boxes, when they were covered in the morning, the amount 
depending somewhat upon the temperature, more being re- 
quired on a cold day when vaporization was slower. From 
fifteen to twenty minutes was found sufficiently long to leave 
the traps covered. If the specimens are to be kept for future 
study, no more gasoline than will readily vaporize should be 
added, for otherwise the specimens will be wet and bedraggled. 
If they are not to be kept, a pint of boiling water poured into 
the crock quickly kills them. 

The position of the trap is very important and upon it de- 
pends its success or failure. Most of the tests were made on 
porches (Fig. 31) at 203 W. Ninth Street, South, and 2300 W. 
Hernando Street, Gainesville, Fla., but traps were tried for 



Spring Number 



55 



short times at several other dwellings in Gainesville, and in 
the dormitories and Experiment Station Building of the 
University of Florida. 

The West Ninth Street house faces west with a porch 
extending entirely across the front. The woodwork is painted 




Plate V. Fig. 27. Crock, or earthenware jar, and box that gave good 
results as traps. Leaning against crock is shown cover consisting of a 
frame and fine wire netting. 

dark green and the porch has a solid coping around it and a 
wire trellis for vines at either end. There are two double 
windows and a door opening on to it. The porch and the 
position of the traps are shown in the diagram, Figure 31a. 
Traps were placed on the south end of the porch on the east 
side next the wall (SE :bc) ; on the west side next the coping 
(SW:bc) and at a point midway between the two. On the 
north end they were located on the east side near the wall 
(NErbbb). 

The house at 2300 W. Hernando Street is situated about one- 
fourth mile northwest of Thomas Hall, University of Florida. 
It faces south with a front porch and a side porch part of the 
way along the east side. The woodwork is white with a door, 
a single window, a double window opening on the front (south) 



56 The Florida Buggist 

porch and two single windows on the side (east) porch. There 
is a corner two feet east of the door that projects outward a 
couple of feet and a trellis of wisteria shades part of the front 
and side porches. The traps were located at the right and 
left of the door (D:rl) ; at the windows on the front (south) 
porch (W:bbb) ; and on the north end of the east porch 
(N:cb). See diagram, Fig. 31b. 

The importance of the position of the traps is strikingly 
shown in Table I, which gives the records of two similar crocks 
situated on the south end of the West Ninth Street porch. One 
was on the east side near the wall (SE :c) and the other not 
eight feet away on the west side near the coping where it was 
more exposed to light (SW:c) (see Fig. 31a). The table 
gives the average number caught per night for a five and six 
months period, from October to March. (There is no record 
for the crock near the coping for November, hence this is for 
a five months period only.) 

TABLE I. — The Effect of Position on the Number Caught 

Average No. Per Night 



Position of Crock (c) 



W. 9th St. at SE:c (1). 
W. 9th St. at SW:c 



Months Recorded 

6 

5 



21.2 
11.3 



(1) See Fig. 31. 

This large difference is explained as follows: As day ap- 
proaches the outer edge of the porch becomes light first and 
the mosquitoes move towards the darker side, next the green 
wall, and eventually settle in the traps. The house also breaks 
the wind on this side and the air is calmer. This tendency to 
go toward the darker side is also shown near the door at 2300 
W. Hernando Street (Fig. 31b). A crock was placed on one 
side of the door and a joint of stovepipe on the other through- 
out the winter. Records for an average of ten nights in 
March show that when the crock was on the right it caught 
1.56 times as many as the stovepipe on the left and that when 
the stovepipe was on the right it caught 1,47 times as many 
as the crock. This is in spite of the fact that a flower stand 
and a box for rubbers, etc., was always on the right and a 
considerable number always settled here. The conditions here 
are somewhat similar to those at West Ninth Street. The pro- 
jecting wall shuts off the early light from the east and the 
wisteria vines, which end about opposite the trap, shut off the 
light from the front, leaving this a darkened corner. The 
effect of a large dark place where the mosquitoes can hide was 



Spring Number 57 

shown at another house. The back porch is. latticed, but not 
screened, and mosquitoes are plentiful. A crock set in various 
places on and about the porch gave almost negative results, as 
most of the mosquitoes settled in a large dark cupboard in a 
corner of the porch. This being larger and equally as dark 
as the jar seemed more attractive. In a bedroom at 203 West 
Ninth Street, where the furniture and walls are light colored, 
four or five, and at once time a dozen mosquitoes were caught 
when they were not numerous enough to be troublesome, 
while in the dormitory, where the woodwork is dark and there 
are closets and bookcases for them to hide in, never more than 
three or four, and often none, would be caught, even when they 
were too numerous for comfort. 

No data were secured on the relation of the direction of the 
wind to the number caught, but the catch was always greater 
on a still than on a windy night. But as a high wind was 
usually accompanied by a drop in temperature, this may 
account for most of the difference. The effect of temperature 
was noticed throughout the winter, a high catch always coming 
with a rise in temperature. The curve in Figure 32 shows 
the temperature recorded and the number caught in a green 
cloth-lined box on the porch at 2300 West Hernando Street 
during February, and the close correlation between the two. 
The temperature of February was the coldest and most varia- 
ble of any month of the year. 

Various substances such as apples, bananas, guavas, raw 
beef, urine, water, banana oil, etc., were placed in the traps as 
attractions, but none caused any appreciable increase in the 
number caught. Very definite results were secured, however, 
with repellants. The method employed was to place a small 
vial, or to pour a little of the substance to be tested in the 
bottom of the trap, and to have a similar trap about a foot 
away for a control, or check. The percentage of efficiency, as 
repellants, of three proprietary compounds, Bombay Vapor, oil 
of citronella and oil of tar, varied from 92.8% to 82% in the 
order named. Traps of this nature should prove useful in 
testing the efficiency of repellants because of the ease in which 
a control can be secured. 

A daily record was kept of the position and the catch of the 
individual traps and the mosquitoes placed in vials or pill 
boxes for future study. Some of the specimens were destroy- 
ed by breakage, loss, destruction by ants, etc., but during the 



58 



The Florida Buggist 



year 20,449 individual mosquitoes were caught and identified. 

Table II gives the number of males and females, the per 

cent of females, the number of females with blood in the 

abdomen, the number of females with well developed ovaries, 





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PORCH 



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Plate VI. Fig. 31. (a) Smaller figure, diagram of porch at 203 W. 
Ninth Street South. Size of porch 9x26 ft. (b) Larger, L-shaped 
figure, diagram of porch at 2300 W. Hernando Street. Size 7 and 9 ft. 
by 28 and 18 ft. (b, c, r, 1, stand for box trap, crock, traps right and left 
of door, respectively.) 



Spring Number 



59 



the total number and the per cent of each species caught during 
the year. 

TABLE II 













xn 

1?*S 














-8 


5° 







Species Caught 






«H 
O 02 


■p c8 


02 o 


1 


«H 
O 




w 


xn 
*3 






3 
fl 






13 




ft 82 




V^3 


■p 

o 


0) ^ 




a 


fc 


0< 


fe 


fe 


H 


Ph 


Culex quinquefasciatus Say. 


11723 


8363 


41+ 


839 


1022 


20086 


98.30+ 


Anopheles quadrima 
















culdtus Say 


26 
37 


171 
124 


86.8 


11 


18 
12 


197 

161 


.96+ 


Anopheles crucians Wied... 


77+ 8 


.78- 


Psorophora ciliata Fab 










2 


.01— 


Stegomyia calopus Meig 






1 




3 


.01+ 


Total 


11786 


8658 


42.33| 858 


1052 


20449 


100.06 



It is seen from the table that Culex quinquefasciatus is the 
dominant species but the percentage given is probably higher 
than is usually found. The relative abundance of the different 
species varies from time to time, but Culex quinquefasciatus 
usually comprises from 80 to 85% of those seen. During 
December very few Culex quinquefasciatus were seen at the 
Experiment Station, while Anopheles were common. Anophe- 
les comprised from 15 to 20% and sometimes more of those 
collected by hand in the dormitories during October and 
November. No Anopheles were found resting on the window 
screens at 2300 West Hernando Street with the Culex until 
about December 1st. From December 1st until February 1st 
both species of Anopheles were found, but usually more 
Anopheles quadrimaculatus. Then Anopheles crucians became 
more abundant, comprising about 10% and sometimes more 
of all those seen. On March 29th, twenty-five Anopheles 
crucians and only two Culex were counted on the screen. Only 
an occasional individual was seen on the screens at 203 West 
Ninth Street, while they were always thick on the screens on 
the front porch at 2300 West Hernando Street, often as many 
as a hundred individuals being counted in the morning before 
they were disturbed. The wisteria vines shade the screens 
at the latter place while there is no such protection at the 
former. 

Stegomyia was occasionally seen in considerable numbers 
about the building, but only three were taken throughout the 

(Continued on page 67) 



Spring Number 



67 



MOSQUITOES FOUND ABOUT GAINESVILLE, FLA. 

(Continued from page 59) 
year in the traps. Psorophora were usually rare, but com- 
prised about 75% of a lot collected by hand or found dead on 
the window sills of the Agricultural Building. They were 
sometimes troublesome at night during May in Science Hall. 
Two or three specimens of Megarhinus were collected, but 
were never taken from traps. 

The percentage of females caught in traps is much lower for 
Culex than for Anopheles. Smith (1) has pointed out that 
male mosquitoes do not fly as far as females and that more 
females than males enter the house. He collected some out- 
side and some inside the house, a total of 1,350, representing 
several species. Of these taken outside, only a small per- 
centage (10-23%) of those breeding considerable distances 
away were males, while 60% of the Culex pipiens, which were 
breeding locally, were males. Of a total of 318 individuals 
taken within the house, Smith did not find a single male. 
Lefroy (2) caught an average of 21.8% females in a similar 
trap set inside the house. 

Culex were found breeding closer to both houses than 
Anopheles. 

TABLE III. — Average Number Caught Per Month in Similar Crocks 

at Both Stations 





Average Number Caught Per Night 


Month 


203 W. Ninth St. S. 


2300 W. Hernando St. 


September, 1912 


21.0 
44.2 
14.3 
14.2 
12.0 
14.5 
31.1 
12.2 
10.5 


30.1 


October 


78.7 


November 


23.2 


December 


32.0 


January, 1913 


15.0 


February 


25.0 


March 


49.0 


April 


30.0 


May 


22.3 






Average per year 


19.3 


33.9 







The number given as having blood in the abdomen included 
only those in which the blood was undigested and could be 
seen through the abdominal walls as a dark clot. All of those 
with the abdomen plump and distended, where no blood could 
be seen, were counted as having well developed ovaries, 
though some of them were probably distended with other food. 



(1). Smith, John B., Annual Report of the Entomologist, Report of the New Jersey 
Experiment Station for 1902. 
(2). See "Literature Cited". 



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Plate VII. Fig. 32. Curves showing correlation between temperature 
and the number of mosquitoes caught per night during February, 1913. 
Figures at left and dotted line denote temperature, degrees F.; figures at 
bottom denote days of the month; figures at right and solid line denote 
the number caught. Porch, 2300 Hernando Street, corner Waukulla 
Avenue, Lot 1, Block 5, College Park Plat, Gainesville, Fla. Trap, a 
box (see Fig, 27) lined with dark green cloth. 



Spring Number 69 

In twenty-five dissections, however, all contained well de- 
veloped eggs, the number varying from 30 to 130, depending 
upon the size of the specimens, with an average of 80.5 eggs. 

In Table III is given the monthly average number caught 
per night in similar crocks situated on the southeast end of 
the porch at 203 West Ninth Street (Fig. 31a SE:c), and on 
the right side of the door at 2300 West Hernando Street (Fig. 
31 b:r). 

Practical Use of Traps 

Traps of this nature may not rid a place of mosquitoes, nor 
even reduce the number enough to make them unobjectionable. 
But in favorable positions, they will catch large numbers and 
certainly could be used as a controlling factor. The average 
number caught throughout the year (September to May) by a 
single crock at 2300 West Hernando Street, was 33.9 per night. 
This would give a total of over twelve thousand for the year. 
Suppose one thousand houses in Gainesville should run two of 
the traps, one on the front porch and one on the back porch, 
for a year. This would rid the city of twenty-four million 
pests — I dare say more than have ever been killed by artificial 
means within the city in the last ten years. Certainly they 
are not so plentiful in Gainesville that these twenty-four 
million would not be missed. But even this is not all; each 
female caught during the winter and spring is cut off from 
becoming the progenitor of at least a thousand others during 
the summer. If every home would cooperate by running one 
or two of these traps, at least during the winter and early 
spring, the number of mosquitoes present would probably be 
greatly reduced. 

Such traps also afford a very convenient means for testing 
the efficiency of repellants and determining the relative abun- 
dance of mosquitoes at different seasons. 

Summary 

1. All of the mosquitoes found at the University breed 
locally, but the breeding areas are small and could be drained 
with the expenditure of a small amount of money. 

2. Traps used for adults, when favorably located on porches, 
have caught an average of thirty-three mosquitoes per night 
for nine months. 

3. Crocks and boxes, black inside or lined with dark cloth, 



70 The Florida Buggist 

have given the best results. They should be rather narrow 
and deep. 

4. The success or failure of traps depends on the location. 
They should be placed in a well lighted room or porch, which 
is free from dark cupboards, closets, etc. The best position 
is determined by experiments. 

5. High winds affect the number caught, but temperature is 
the most important factor. The largest numbers caught were 
on warm still nights. 

6. Not all species are equally attracted to the traps. Culex 
quinquefasciatus is attracted more than Anopheles or 
Stegomyia. 

7. These traps are not recommended to rid a place of mos- 
quitoes, but if used with judgment they will reduce the num- 
ber present in the house or outside. Such traps are also useful 
for collecting mosquitoes for specimens, demonstration or 
class uses, or for testing repellants. 

Literature Cited 

Berkley, W. N., 1902, Laboratory Work With Mosquitoes. 

Darling, Samuel T., 1910, Studies in Relation to Malaria. Publication of 

the Isthmian Canal Commission, Laboratory of the Board of Health, 

Department of Sanitation. 
Davis, J. J., 1906, The Number of Eggs of Culex Pipiens. Entomological 

News, Vol. 17, No. 10, p. 368. 
Felt, E. P., 1910, Report of the N. Y. State Entomologist for 1905. 
Francis, 1906, Public Health Notes, Vol., No. 26, June, 1909. 
Gorgas, W. C, 1909, Larvaecides. Report of the Department of the 

Isthmian Canal Zone for 1912. 
Gorgas, W. C, 1909, Larvaecides. Report of the Department of Sanita- 
tion of the Isthmian Canal Zone for 1909. 
Herrick, Glen. W., 1903, The Relation of Malaria to Agriculture and 

Other Industries of the South. Popular Science Monthly, April, 1903. 
Howard, L. O., 1909, Mosquitoes; How They Live; How They Carry 

Disease; How They Are Classified; How They May Be Destroyed. 
Howard, L. O., 1910, Preventive and Remedial Work Against Mosquitoes. 

Bureau of Entomology, U. S. D. A. Bulletin 88. 
Howard, L. O., 1911, Some Facts About Malaria, U. S. D. A. Farmers' 

Bulletin 450. 
Johnson, H. P., 1902, A'Study of Certain Mosquitoes in New Jersey and 

a Statement of the "Mlosquito-Malaria" Theory. Appendix A., N. 

J. Agricultural Experiment Station. Report of the Entomologist 

for 1902. 
Lefroy, H. Maxwell, 1907, A Preliminary Account of the Biting Flies of 

India, Agricultural Research Institute. Pusa, India, Bulletin 7. 
Lugger, Otto, 1896, Report of the Entomologist Maine Agricultural 

Experiment Station, Report for 1896. 



Spring Number 71 

Mitchell, Evelyn Groesbeck, 1907, Mosquito Life. 

Quayle, H. J., 1906, Mosquito Control. California Agricultural Experi- 
ment Station Bulletin 178. 

Smith, John B., 1901-1911, Reports of the Entomologist for 1901-1911. 
New Jersey Agricultural Experiment Station. 

Smith, John B., 1908. The House Mosquito, A City, Town, and Village 
Problem. New Jersey Agricultural Experiment Station Bulletin 246. 

Theobald, F. V., 1901, Monograph of the Culicidae, or Mosquitoes. 
Official Publication of the British Museum, London. 

Van Dine, D. L., 1906, Mosquito Control. The Introduction of Top 
Minnows in the Hawaiian Islands. Hawaiian Station Report Press 
Bulletin 20. 



KEY TO NORTH AMERICAN SPECIES OF PHYSOTHRIPS 

(Continued from page 32) 

The genus Physothrips is part of the old genus Euthrips which name 
Karny (1909) has shown should be applied to the genus Anaphothrips. 
The species formerly included under Euthrips are now divided between 
four genera which may be separated by the following key : 

1. Tibia with a strong, curved spine on the end Odontothrips Serville 

2. Tibia without such a spine. 

a. Wings with transverse bands Taeniothrips Serville 

aa. Wings without transverse bands. 

b. Bristles on the fore angles of the prothorax conspicuous. 

Frankliniella Karny 
bb. Bristles on the fore angles of the prothorax not conspicuous. 

Physothrips Karny 

KEY TO THE NORTH AMERICAN SPECIES OF PHYSOTHRIPS 

(Adapted from Jones, 1912) 

1. General color white to light yellow or orange. Head noticeably wider 
than long. 

a. Last two segments of antennae rather long and slender, and to- 
gether about 2-3 as long as segment 6. Wings shaded brown except 

near base and apex P. orchardii (Moulton) 

aa. Last two segments of antennae not long and slender, about Vz as 
long as segment 6. Wings not shaded brown, 
b. Ring vein and longitudinal veins conspicuous. Wings dilute 

yellow P. costalis (Jones) 

bb. Ring and longitudinal veins not conspicuous. Wings white. 

P. albus (Moulton) 

2. General color brown. 

a. Head nearly as long as wide; no prominent bristles in front of 

posterior ocelli P. longirostrum (Jones) 

aa. Head noticeably wider than long; a prominent spine in front of each 
posterior ocellus. 

b. Eyes not pilose; postocular bristles present; antennal segments 
3 and 4 not pedicellate; posterior longitudinal vein of fore wings 

with 13 spines P. ehrhornii (Moulton) 

bb. Eyes sparsely pilose; post-ocular bristles absent; antennal seg- 
ments 3 and 4 pedicellate; posterior longitudinal vein with 11 or 
12 spines P. blacki n. sp.